<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>JavaScript Document</title>
    <script type="text/javascript" src="javascript.js">
    </script>
    <!-- if JavaScript is here then it becomes a global variable(全局变量)-->
</head>
<body onload="show()">  
    <!-- When the web is open this founction occur -->
    <!-- if JavaScript is here then it becomes a action mode-->
    <button class="changecolor"></button>
</table>
<table class="colortable" border="1" height="168" width="168"></table>
<tr><td></td></tr>
</body>
</html>